Enzymatic Synthesis And Property Research Of Propylene Glycol Monoesters By Alcoholysis Of Coconut Oil

Propylene glycol esters of fatty acids (PGMS) are good water-in-oil emulsifiers, havinglow hydrophilic-lipophilic balance values. As food additives, these emulsifiers have beenapproved by the U.S. Food and Drug Administration (FDA) and FAO/WHO. They haveimportant applications in the preparation of cakes, cake mixes, bread, margarines, shortening,chocolate, ice cream, ect., which has good economic benefit and a broad prospects in foodindustry. At present, PGMS are commercially produced by chemical synthesis catalyzed byinorganic catalyst with drawbacks of dark by-products, off-flavors, toxicity and low purity.While the lipases-mediating biosynthesis of PGMS offer several advantages such as milderoperating conditions, high molar conversion, clean products, and reduced waste production.Inthis dissertation, a enzymatic process for the production of propylene glycol esters of fattyacids is proposed. The main contents of this dissertation were as follows:1、Through lipase screening, Novozyme435was determined as the catalyst for theenzymatic synthesis reaction. Using Novezyme435as the catalyzer, a research was conductedon several factors in sovent-free system: substrate molar ratio, reaction temperature, enzymaeloading and water content. The optimum condition for PGMS was coconut oil/1,2-propyleneglycol1:8(mol/mol), reaction temperature50℃, enzyme loading300U/g substrate, watercontent in propylene glycol1%. Under these conditions, the yield53.17%of coconut-oilbased PGMS was obtained at3h.2. The crude enzymatic reaction product was purified by two steps moleculardistillation.Through single factor experiment, the optimum conditions for moleculardistillation was: first step condition: evaporation temperature80℃,condensing surfacetemperature15℃, feed flow rate1.5mL/min,system pressure35-40Pa；Second step condition:evaporation temperature110℃,condensing surface temperature15℃, feed flowrate1.5mL/min,system pressure8Pa.Under these conditons, the content of93.15%Coconutoil-based propylene glycol monesters was obtained.3. Physical and chemical analysis of purified product was conduted and emulsificationand emulsion stability of product were expored. Results indicted that Physical and chemicalindex of purified product was up to quality requirements of food additive standards.The HLBvalue was3.44, which showed good emulsifying properties and good emulsion stability. Theproduct also has inhibiting effect on milk rancidity mixed strains.4. The application of coconut oil-based propylene glycol monesters in margarine was studed by DSC ananlysis, X-ray diffraction analysis, polarized light microscopy (PLM).Added coconut oil-based propylene glycol monesters, margarine quality improved in a certainextent.